Show which argument is non-hot

Author: liufengyun

compiler/src/dotty/tools/dotc/transform/init/Errors.scala

@@ -101,8 +101,22 @@ object Errors:
         error.show
 
   /** Unsafe leaking a non-hot value as constructor arguments */
-  case class UnsafeLeaking(trace: Seq[Tree], error: Error) extends Error:
+  case class UnsafeLeaking(trace: Seq[Tree], error: Error, argsIndices: List[Int]) extends Error:
     def show(using Context): String =
-      "Problematic object instantiation with uninitialized arguments." + stacktrace() + "\n" +
+      "Problematic object instantiation: " + argumentInfo() + stacktrace() + "\n" +
         "It leads to the following error during object initialization:\n" +
         error.show
+
+    private def argumentInfo(): String =
+      val multiple = argsIndices.size > 1
+      val part1 =
+        argsIndices.zipWithIndex.foldLeft("") { case (acc, (pos, i)) =>
+          val text1 = if pos == 0 then "the outer" else "arg " + pos.toString
+          val text2 =
+            if i == argsIndices.size - 2 then text1 + " and "
+            else if i == argsIndices.size - 1 then text1
+            else text1 + ", "
+          acc + text2
+        }
+      val part2 = if multiple then " are not fully initialized." else " is not fully initialized."
+      part1 + part2

compiler/src/dotty/tools/dotc/transform/init/Semantic.scala

@@ -784,7 +784,15 @@ object Semantic:
           warm.callConstructor(ctor, argInfos2)
         }
         if errors.nonEmpty then
-          val error = UnsafeLeaking(trace.toVector, errors.head)
+          val indices =
+            for
+              (arg, i) <- argValues.zipWithIndex
+              if arg.isCold
+            yield
+              i + 1
+
+          val indices2 = if warm.outer.isHot then indices else 0 :: indices
+          val error = UnsafeLeaking(trace.toVector, errors.head, indices2)
           reporter.report(error)
           Hot
         else

tests/init/neg/cycle-structure.check

@@ -1,7 +1,7 @@
 -- Error: tests/init/neg/cycle-structure.scala:9:13 --------------------------------------------------------------------
 9 |    val x = A(this)   // error
   |            ^^^^^^^
-  |            Problematic object instantiation with uninitialized arguments. Calling trace:
+  |            Problematic object instantiation: arg 1 is not fully initialized. Calling trace:
   |            -> case class B(a: A) {	[ cycle-structure.scala:7 ]
   |               ^
   |            -> val x = A(this)   // error	[ cycle-structure.scala:9 ]
@@ -16,7 +16,7 @@
 -- Error: tests/init/neg/cycle-structure.scala:3:13 --------------------------------------------------------------------
 3 |    val x = B(this)   // error
   |            ^^^^^^^
-  |            Problematic object instantiation with uninitialized arguments. Calling trace:
+  |            Problematic object instantiation: arg 1 is not fully initialized. Calling trace:
   |            -> case class A(b: B) {	[ cycle-structure.scala:1 ]
   |               ^
   |            -> val x = B(this)   // error	[ cycle-structure.scala:3 ]

tests/init/neg/i15363.check

@@ -1,7 +1,7 @@
 -- Error: tests/init/neg/i15363.scala:3:10 -----------------------------------------------------------------------------
 3 |  val b = new B(this) // error
   |          ^^^^^^^^^^^
-  |          Problematic object instantiation with uninitialized arguments. Calling trace:
+  |          Problematic object instantiation: arg 1 is not fully initialized. Calling trace:
   |          -> class A:	[ i15363.scala:1 ]
   |             ^
   |          -> val b = new B(this) // error	[ i15363.scala:3 ]

tests/init/neg/secondary-ctor4.check

@@ -1,7 +1,7 @@
 -- Error: tests/init/neg/secondary-ctor4.scala:54:14 -------------------------------------------------------------------
 54 |      val c = new C(b, 5)   // error
    |              ^^^^^^^^^^^
-   |              Problematic object instantiation with uninitialized arguments. Calling trace:
+   |              Problematic object instantiation: the outer and arg 1 are not fully initialized. Calling trace:
    |              -> class N(d: D) extends M(d) {	[ secondary-ctor4.scala:59 ]
    |                 ^
    |              -> def this(d: D) = {	[ secondary-ctor4.scala:7 ]
@@ -30,7 +30,7 @@
 -- Error: tests/init/neg/secondary-ctor4.scala:42:4 --------------------------------------------------------------------
 42 |    new A(new B(new D))  // error
    |    ^^^^^^^^^^^^^^^^^^^
-   |    Problematic object instantiation with uninitialized arguments. Calling trace:
+   |    Problematic object instantiation: the outer and arg 1 are not fully initialized. Calling trace:
    |    -> class N(d: D) extends M(d) {	[ secondary-ctor4.scala:59 ]
    |       ^
    |    -> def this(d: D) = {	[ secondary-ctor4.scala:7 ]